7. Project Summary/Abstract Melissa Chen, MD, MPH is an Assistant Professor in the Department of Obstetrics and Gynecology at UC Davis who completed fellowship training in family planning in June 2016. She is seeking this Career Development Award to establish herself as an independent investigator in postpartum contraception with a specific focus on lactation as a contraceptive method. This K23 award enables Dr. Chen to achieve her career goal through the following objectives: (1) to broaden her understanding of clinical research through coursework, (2) to diversify her research skills with experience in conducting different types of patient-oriented contraception studies, and (3) to facilitate her professional development into an academic researcher. Dr. Chen has assembled a team of mentors and advisors to guide her through her research and career development. Her primary mentor is Dr. Mitchell Creinin, an expert in contraceptive clinical trials, and her co-mentor is Dr. Eleanor Bimla Schwarz, who has expertise in lactation on maternal health and qualitative research methods. Research: Postpartum contraception plays a role in determining interpregnancy intervals, but lactation experts express concerns that early initiation of hormonal contraception may adversely affect breastfeeding. The lactational amenorrhea method (LAM) is an effective initial method of contraception; however, the extent to which women who are pumping can rely on LAM is unknown. This issue is particularly relevant to mothers of preterm infants who are at risk of recurrent preterm birth and who often delay hormonal contraception while pumping breast milk. The proposed research will improve counseling about LAM as a contraceptive method by: (1) understanding differences in ovarian suppression between mothers who are breastfeeding (i.e. feed at the breast) and those who are pumping breastmilk and (2) exploring whether these differences exist between mothers who deliver preterm compared to those who deliver at term. This goal will be accomplished with 3 aims. The first aim is to compare amenorrhea rates, duration of lactation, and resumption of sexual activity among postpartum women who are breastfeeding versus expressing milk after term and preterm delivery through a prospective observational study following women through 6 months postpartum. The second aim is to conduct a pilot study assessing the feasibility and acceptability of using home urinary luteinizing hormone test kits to detect ovulation in exclusively breastfeeding women. Serum progesterone levels will be drawn to confirm ovulation, and the average time to ovulation as determined with this technology will be assessed. The third aim is to understand decision-making regarding contraception and infant feeding practices in mothers of preterm infants using a qualitative approach with semi-structured interviews. Findings from these proposed studies will form the basis for a potential R01 grant application for a multicenter contraceptive clinical trial on the efficacy of LAM in mothers of term and preterm infants who are pumping breastmilk.